TWI816370B - Optical system and aiming equipment - Google Patents

Abstract

The present invention discloses an optical system and aiming device. The optical system comprises: a wavefront modulation element having opposing first and second surfaces, the first surface of the wavefront modulation element is used for receiving a first light wave without a complete plane wavefront, and the second surface of the wavefront modulation element is used for emitting a second light wave with a complete plane wavefront which is beam shaped by the wavefront modulation element from the first light wave. The aiming equipment includes a housing and an optical system disposed in the housing. In the embodiment of the present invention, the size constraint of each element of the optical system can be reduced, while at the same time ensuring that the image quality will not be degraded.

Description

An optical system and aiming device

The invention belongs to the field of optoelectronics technology, and in particular relates to an optical system and aiming equipment.

Optical systems composed of waveguides carrying incident gratings and exit gratings are used in many fields. In such an optical system, light enters the waveguide through the incident grating. The light incident into the waveguide is parallel light. The parallel light propagates in the waveguide. When the parallel light propagates to the exit grating, it is coupled out of the waveguide. The image quality of the light coupled out of the waveguide is not high without a complete plane wave.

Embodiments of the present invention provide an optical system and a sighting device. The optical system includes: a wavefront modulation element having opposite first and second surfaces, the first surface of the wavefront modulation element being configured to receive a wave without a complete plane. In front of the first light wave, the second surface of the wavefront modulation element is configured to emit a second light wave with a complete plane wavefront that passes through the wavefront modulation element to perform beam shaping on the non-complete plane wavefront. The aiming device includes a housing and the above-mentioned optical system arranged in the housing.

The objects, and features of the present invention will be set forth in the description which follows, to the extent that they will become apparent to those of ordinary skill in the art upon examination of the following, Or may be taught by practicing the invention. The objectives and other advantages of the present invention may be realized and obtained by the structure particularly pointed out in the following description, claims, and drawings.

The embodiments of the present invention will be described in detail below with reference to the drawings and examples, so that the implementation process of how to apply technical means to solve technical problems and achieve corresponding technical effects of the present invention can be fully understood and implemented accordingly. The embodiments of the present invention and various features in the embodiments can be combined with each other without conflict, and the resulting technical means are within the protection scope of the present invention.

Please refer to Figure 1. H1 is the coupling input grating, H2 is the coupling output grating, and the coupling output grating H2 has an image. The coupling-in grating H1 and the coupling-out grating H2 are respectively attached to the same surface of the waveguide 300'. The coupling input grating H1, the coupling output grating H2 and the waveguide 300' form an optical system. The parallel light is incident on the coupling-in grating H1 and is coupled into the waveguide 300' through the coupling-in grating H1. The parallel light is transmitted through total reflection in the waveguide. When the parallel light reaches the coupling output grating H2, the coupling output grating H2 couples the parallel light from the waveguide 300' to the human eye. The range of parallel light emitted from the coupling output grating H2 is called the Eyebox. Among them, the beam width PD of the incident parallel light is consistent with the beam width PD of the outgoing parallel light, the angle at which the light propagates in the waveguide 300' is θ, and the total reflection period of the light propagating in the waveguide 300' is is the thickness of the waveguide 300'.

The above optical system can be applied in a waveguide holographic aiming device. The light input from the waveguide 300' to the surface of the coupling output grating H2 needs to have a plane wavefront (wavefront). At this time, the coupling output grating H2 can be clearly seen without distortion in the far field. The image is diffracted (because plane waves are used for recording), and the plane wavefront represents a linear distribution of the phase distribution of the light wave. Normally, human eye observation requires a larger eyebox size, such as 25mm*25mm. In order to ensure a plane wavefront, it is required that the coupling input grating H1 on the waveguide 300' needs to be the same size as the coupling output grating H2, that is, 25mm* 25mm, and the beam width PD of the parallel light propagating in the waveguide 300' must be the same size on the surface of the coupling input grating H1 and the surface of the coupling output grating H2, and the total reflection period of transmission L must be greater than or equal to the beam width PD of the incident parallel light. , the total reflection period L of transmission is related to the thickness D of the waveguide 300'. If the angle θ of transmission in the waveguide 300' does not change, the thickness D of the waveguide 300' is also required to be thicker to ensure a plane wave front. These factors all lead to the need to increase the horizontal or vertical size of each element in the optical system in order to obtain good enough image quality and enough eyeboxes, which undoubtedly leads to the disadvantage of a large optical system. If the plane wavefront cannot be guaranteed, the final image will be distorted and blurred, affecting the final aiming effect.

In order to provide a new method that can reduce the size constraints of each element of the optical system, solve the above problems in the waveguide aiming device, and ensure that the image quality is not reduced at the same time, an embodiment of the present invention discloses an optical system, which includes: A first surface and a second surface of the wavefront modulation element 500, the first surface of the wavefront modulation element 500 is configured to receive the first light wave that does not have a complete plane wavefront, and the second surface of the wavefront modulation element 500 is configured to emit through The wavefront modulation element 500 beam-shapes the first light wave into a second light wave having a complete plane wavefront.

The wavefront modulation element 500 performs beam shaping on the first light wave that does not have a complete plane wavefront, and can obtain a second light wave by performing beam shaping on the amplitude and phase of the first light wave, and the second light wave has a complete plane wavefront. The second light wave emerging through the second surface of the wavefront modulation element 500 may be arranged to illuminate the layer element 600 (Fourier hologram), the layer element 600 being arranged to receive the second light wave and present the image recorded by the layer element 600 , the layer element 600 Images can be rendered with high quality. Since the wavefront modulation element 500 can modulate a first light wave without a complete plane wavefront into a second light wave with a complete plane wavefront, the wavefront modulation element 500 can be used with an optical system that emits a first light wave without a complete plane wavefront, The size of the optical system that emits the first light wave without a complete plane wavefront is not limited by the lateral size or the longitudinal size, and the volume of such an optical system can be more compact.

In some embodiments, the first light wave includes a plurality of segmented plane waves, and at least two adjacent plane waves in the plurality of segmented plane waves partially overlap. Segmented plane waves do not have a complete plane wavefront. For example, the optical system shown in FIG. 2 includes a waveguide 300 and a coupling-in grating 401 and a coupling-out grating 402 attached to the same surface of the waveguide 300 . The parallel light is incident on the coupling-in grating 401 and is coupled into the waveguide 300 through the coupling-in grating 401. The parallel light is transmitted through total reflection in the waveguide 300. When the parallel light reaches the coupling-out grating 402, the coupling-out grating 402 couples the parallel light out from the waveguide 300 to the human eye. The range of parallel light emitted from the coupling-out grating 402 is called an eyebox. The beam width PD of the incident parallel light may be greater than the total reflection period of the light propagating in the waveguide 300 as , the angle at which light propagates in the waveguide 300 is θ, and D is the thickness of the waveguide 300 . The first light wave emitted through the coupling output grating 402 includes a first segmented plane wave (1st) and a second segmented plane wave (2nd). The first segmented plane wave and the second segmented plane wave overlap. The beam complex amplitude field of the first light wave includes the sum of two segmented plane waves, and each segmented plane wave field has a total wave field with different amplitudes and different phases.

The first segmented plane wave has a plane wave front ,in, is the first segmented plane wave in Amplitude distribution at location, is the first segmented plane wave in Phase distribution at location. The second segmented plane wave has a plane wave front ,in, is the second segmented plane wave in Amplitude distribution at location, is the second segmented plane wave in Phase distribution at location. wavefront of first light wave , for the first light wave in Amplitude distribution at location, for the first light wave in Phase distribution at location. By beam shaping the amplitude and phase of the first light wave, the wavefront modulation element 500 can modulate the first light wave without a complete plane wavefront into a second light wave with a complete plane wavefront.

In some embodiments, in order to increase the comfort of use, the size of the Eyebox can be increased, for example, by expanding the light beam multiple times in the waveguide 300. The first light wave does not have a complete plane wavefront, and the first light wave is ,in, for the first segmented in The light wave at the location, for the first light wave in Amplitude distribution at location, for the first light wave in Phase distribution at location. In order to make the second light wave emitted through the second surface of the wavefront modulation element 500 have a plane wavefront, the second light wave is ,in, is a constant, is a proportional function, and the wavefront modulation element 500 has a complex amplitude transmittance , where the amplitude transmittance distribution of the wavefront modulation element 500 , the phase distribution of the wavefront modulation element 500 ,in, is an integer.

The second light wave emitted through the second surface of the wavefront modulation element 500 , in order to ensure that the emitted second light wave is a plane wavefront, it is required The amplitude of is constant, The phase of is a linear phase, that is: . in, is a constant, is a proportional function, for example, , is the wave number, is the angle of incidence to layer element 600. When the incidence is normal, . The wavefront phase distribution of the recording light of the layer element 600 is . Wavefront modulation element 500 achieves complex amplitude transmittance at each position modulation, where the amplitude transmittance of the wavefront modulation element 500 , the phase distribution of the wavefront modulation element 500 , It is a degree of freedom for phase design, which does not affect the effect of phase adjustment.

In some embodiments, layer element 600 receives the second light wave and renders the image recorded by layer element 600 . Layer element 600 (Fourier hologram) can be recorded by a planar wavefront. To record Fourier holograms, plane waves are chosen. On the one hand, plane waves are easy to obtain, and on the other hand, a constant phase can be added to the plane wave front. Therefore, in actual use, it only needs to be incident on the hologram at the correct angle. The second light wave emitted is modulated by the wavefront modulation element 500 is a plane wavefront. When it is illuminated on the layer element 600, the Fourier spectrum light of the object can be obtained. , the wavefront phase distribution of the light recorded by the layer element 600 is , so the human eye can observe the image intensity distribution , that is: , FT is the Fourier transform process, || is the modular operation.

In some embodiments, the wavefront modulation element 500 can be fabricated through a holographic fabrication process. The wavefront modulation element 500 is provided with complex amplitude transmittance using a holographic manufacturing process. .

In some embodiments, referring to Figure 3, wavefront modulation element 500 includes a first optical element 501 and a second optical element 502, the first optical element 501 having an amplitude transmittance distribution , the second optical element 502 has a phase distribution . The wavefront modulation element 500 can respectively modulate the amplitude and phase through two optical elements. The first optical element 501 and the second optical element 502 may be made using a holographic manufacturing process.

In some embodiments, the first optical element 501 and the second optical element 502 are bonded together, and the first surface is located on a side of the first optical element 501 away from the second optical element 502 or on a side far away from the second optical element 502 On one side of the first optical element 501 , the second surface is located on the side of the second optical element 502 away from the first optical element 501 or on the side of the first optical element 501 away from the second optical element 502 . The first optical element 501 is configured to modulate the amplitude, and the second optical element 502 is configured to modulate the phase. The first light wave may first enter the second optical element 502 for phase modulation, and then enter the first optical element 501 for amplitude modulation to obtain the second light wave. Alternatively, the first light wave may first enter the first optical element 501 for amplitude modulation, and then enter the first optical element 501 for amplitude modulation. It enters the second optical element 502 for phase modulation to obtain a second light wave.

In some embodiments, referring to FIGS. 4 and 5 , the optical system includes a wavefront modulation element 500 as well as a light source 101 , a coupling-in element 401 , a waveguide 300 , a coupling-out grating 402 , and a layer element 600 . The light source 101 is configured to emit light; the coupling element 401 is configured to receive the light emitted by the light source 101 and refract the light; the waveguide 300 is configured to receive the light refracted by the coupling element 401 and transmit it in the waveguide 300 in a manner that is greater than the total reflection angle. Propagate light; the coupling-out grating 402 is configured to couple the light propagating in the waveguide 300 out of the waveguide 300, and the light emitted from the waveguide 300 is the first light wave; the layer element 600 is configured to receive the second light wave and present the image recorded by the layer element 600. The first light wave is modulated by the wavefront modulation element 500 to form a second light wave. The second light wave irradiates the layer element 600, and the image enters the human eye 700. The human eye 700 can observe a clear and distortion-free image 701.

The coupling-in element 401 refracts the light emitted by the light source 101 into parallel light and enters the waveguide 300 . The parallel light propagates in the waveguide 300 until it encounters the coupling-out grating 402 and couples the parallel light out of the waveguide 300 . The first light wave emitted through the coupling-out grating 402 may not have a complete plane wavefront, so the beam sizes of the coupling-in element 401 and the coupling-out grating 402 are not required to be consistent. The surface beam diameter of the coupling-out grating 402 may be much larger than that of the coupling-in element 401 The surface beam input aperture, the total reflection period L of light propagating in the waveguide 300 can be smaller than the width PD of the incident beam. Referring to Figure 2, the beams hitting the coupling output grating 402 twice can overlap, and finally the coupling output grating 402 can overlap. The emerging ray from the 402 surface does not have a complete plane wavefront (but is segmented). The size of each element of the optical system can be reduced, and the overall volume of the optical system can be more compact. For example, the size of the coupling input element 401, the thickness of the waveguide 300, and the volume of the collimation system that often generates input light can be effectively reduced, while the layer The quality of the image emitted by the element 600 can also be guaranteed.

Wherein, the coupling-in element 401 and the coupling-out grating 402 are respectively arranged parallel to at least one plane of the waveguide 300 . For example, when the coupling-in element 401 is a coupling-in grating, the coupling-in grating and the coupling-out grating 402 are respectively arranged parallel to two opposite planes of the waveguide 300 , or the coupling-in grating and the coupling-out grating 402 are both aligned with one plane of the waveguide 300 . Parallel setting. Both the coupling-in element 401 and the coupling-out grating 402 are arranged closely with the waveguide 300 . For example, when the coupling-in element 401 is a coupling-in grating, the coupling-in grating and the coupling-out grating 402 can be attached to one side of the waveguide 300 (refer to FIG. 4 ), or the coupling-in grating and the coupling-out grating 402 can be attached to the waveguide 300 respectively. both sides. The coupling-in grating can be attached to the coupling-out grating 402 on the side of the waveguide 300 close to the human eye 700 , and the coupling-in grating can also be attached to the coupling-out grating 402 on the side of the waveguide 300 away from the human eye 700 .

The wavefront modulation element 500 and the layer element 600 are disposed on the side close to the human eye 700 . The wavefront modulation element 500 and the layer element 600 are arranged in parallel. The wavefront modulation element 500 and the coupling-out grating 402 are arranged in parallel. If the outcoupling grating 402 is disposed on the side of the waveguide 300 close to the human eye 700 , the first surface of the wavefront modulation element 500 can be attached to the outcoupling grating 402 . The coupling-out grating 402 may be disposed on a side of the waveguide 300 away from the human eye 700 , and the first surface of the wavefront modulation element 500 may have a predetermined distance from the waveguide 300 .

The waveguide 300 can be made of transparent optical plastic or glass, which has a refractive index n, and the transmission angle θ of light in the waveguide 300 satisfies , the light can propagate in the waveguide 300 in a total reflection manner. The coupling-out grating 402, the wavefront modulation element 500 and the layer element 600 can all transmit ambient light, and the human eye 700 can see the real ambient light through the waveguide 300, the coupling-out grating 402, the wavefront modulation element 500 and the layer element 600.

In some embodiments, the second surface of the wavefront modulation element 500 is disposed in contact with the layer element 600 . The second surface of the wavefront modulation element 500 emits a second light wave. The second light wave has a complete plane wavefront. The second light wave irradiates the layer element 600 and the human eye 700 can see the image recorded by the layer element 600 .

In some embodiments, referring to Figure 4, light source 101 may be a point light source. The point light source 101 emits monochromatic light into the coupling grating, and is refracted into the waveguide 300 through the coupling grating to obtain parallel light transmitted in the waveguide 300 .

In some embodiments, the optical system further includes a collimating element 201. The collimating element 201 is disposed in the optical path between the light source 101 and the coupling-in element 401. The collimating element 201 is configured to collimate the light emitted by the light source 101 and The collimated light is emitted toward the coupling-in element 401 . The collimating element 201 can collimate the light emitted by the point light source 101 into parallel light, and the coupled input grating refracts the parallel light into the waveguide 300 .

In some embodiments, referring to FIG. 5 , the coupling element 401 included in the optical system may be a coupling element that refracts the light emitted by the light source 101 into the waveguide 300 . The coupling input grating 402 can be coupled to one side of the waveguide 300, and the coupling output grating 402 can be coupled to the other side of the waveguide 300. The two surfaces are not parallel. In addition, the optical system may also include a collimating element 201. The collimating element 201 is disposed in the optical path between the light source 101 and the coupling input lens. The collimating element 201 is used to collimate the light emitted by the light source 101 and collimate the light. The light rays are emitted toward the coupling inlet, which refracts the collimated light into the waveguide 300 . Both the collimating element 201 and the light source 101 may be positioned close to the side of the waveguide. Coupling input gratings instead of coupling input gratings can improve light energy utilization.

In some embodiments, the length at which the coupling-out grating 402 is coupled to the waveguide 300 is greater than the length at which the coupling-in element 401 is coupled to the waveguide 300 . The size of the optical system can be reduced, but the image quality will not be reduced. The human eye can see clear and distortion-free images.

In the above-mentioned optical system, the layer element 600 presents a aiming image (image) that can be used in a holographic aiming device. The holographic aiming device includes a housing and the above-mentioned optical system, and the optical system is arranged in the housing. Such a holographic aiming device can take advantage of the foldable optical path of the holographic waveguide and the easy integration of gratings, reducing the size of the holographic aiming device and lifting the limitations of traditional waveguide aiming on components without reducing image quality.

The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Anyone with ordinary knowledge in the relevant technical field can easily think of various solutions within the technical scope disclosed in the present invention. Any changes or substitutions shall be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the patent application.

101: Light source 201: Collimation element 300, 300': Waveguide 401: Coupling element (Fig. 2) 500: Wavefront modulation element 501: First optical element 502: Second optical element 600: Layer element 700: Human eye 701: Figure Image D: thickness PD: beam width H ₁ , 401: coupling input grating (Fig. 4) H ₂ , 402: coupling output grating L: total reflection period of transmission 2nd: second segmented plane wave 1st: first segmented plane wave

The drawings are used to provide a further understanding of the technical means of the present invention or the prior art, and constitute a part of the specification. Among them, the drawings expressing the embodiments of the present invention are used together with the embodiments of the present invention to explain the technical means of the present invention, but do not constitute a limitation on the technical means of the present invention. [Figure 1] is a schematic structural diagram of an optical system. [Figure 2] is a schematic structural diagram of another optical system. [Fig. 3] is a schematic structural diagram of a wavefront modulation element according to an embodiment of the present invention. [Fig. 4] is a schematic structural diagram of an optical system according to an embodiment of the present invention. [Fig. 5] is a schematic structural diagram of an optical system according to another embodiment of the present invention. [Fig. 6] is a schematic diagram of a aiming device according to an embodiment of the present invention.

101:Light source

201:Collimation element

300:Waveguide

401: Coupling input element

402: Coupling output grating

500: Wavefront modulation element

600:Layer component

700: human eye

701:Image

Claims (10)

An optical system, characterized by comprising: a wavefront modulation element (500) having opposite first and second surfaces, wherein the first surface of the wavefront modulation element (500) is configured as a receiving waveguide (300) The first light wave that does not have a complete plane wavefront is emitted from the coupling output grating (402), and the second surface of the wavefront modulation element (500) is configured to emit the first light wave through the wavefront modulation element (500). A second light wave having a complete plane wavefront for beam shaping; wherein the first light wave includes a plurality of segmented plane waves, and at least two adjacent plane waves in the plurality of segmented plane waves partially overlap. The optical system as claimed in claim 1, wherein the first light wave is

, where W _n ( x ) is the n -th segmented light wave at the x position, A ( x ) is the amplitude distribution of the first light wave at the x position, φ ( x ) is the first light wave at the x position The phase distribution at the position; the second light wave is V ( x ) = α exp [ iβ ( x )], where α is a constant, β ( x ) is a proportional function, and the wavefront modulation element (500) has a complex amplitude transmittance

, where the amplitude transmittance distribution of the wavefront modulation element (500)

, the phase distribution of the wavefront modulation element (500)

, where m is an integer. The optical system according to claim 2, wherein the wavefront modulation element (500) is processed through a holographic manufacturing process. The optical system according to claim 2, wherein the wavefront modulation element (500) includes a first optical element (501) and a second optical element (502), and the first optical element (501) has an amplitude transmittance distribution

, the second optical element (502) has a phase distribution

. The optical system of claim 4, wherein the first optical element (501) and the second optical element (502) are bonded together, and the first surface is located away from the first optical element (501). One side of the second optical element (502) or a side of the second optical element (502) away from the first optical element (501), and the second surface is located on a side of the second optical element (502) away from the first optical element (501). One side of the first optical element (501) or a side of the first optical element (501) away from the second optical element (502). The optical system according to any one of claims 1 to 5, wherein the optical system further includes: a light source (101) configured to emit light; a coupling-in element (401), the coupling-in element (401) is configured to receive the light emitted by the light source (101) and refract the light; the waveguide (300), the waveguide (300) is configured to receive the refracted light of the coupling input element (401) and refract the light in the waveguide (300). The light propagates in 300) in a manner greater than the total reflection angle; the coupling output grating (402), the coupling output grating (402) is configured to couple the light propagating in the waveguide (300) out of the waveguide (300), where, The light emitted from the waveguide (300) is the first light wave; the layer element (600) is configured to receive the second light wave and present the image recorded by the layer element (600); wherein, the coupling The input element (401) and the coupling output grating (402) are both connected to the waveguide (300) Fit settings. The optical system as claimed in claim 6, wherein the coupling-in element (401) is selected from the group consisting of a coupling-in grating and a coupling-in lens; wherein the optical system further includes a collimating element (201), The collimating element (201) is arranged in the optical path between the light source (101) and the coupling element (401). The collimating element (201) is arranged to collimate the light emitted by the light source (101) and The collimated light is emitted toward the coupling-in element (401). The optical system as claimed in claim 6, wherein the second surface of the wavefront modulation element (500) is arranged in contact with the layer element (600). The optical system as claimed in claim 6, wherein the coupling-out grating (402) and the waveguide (300) are bonded together for a length greater than the coupling-in element (401) and the waveguide (300). A sighting device is characterized by including a housing and the optical system as described in claim 1, wherein the optical system is disposed in the housing.